The default behavior for a function in Mathematica is carefully chosen to be suitable for the vast majority of cases. Mathematica also gives you fine-grained control over the ...
BesselYZero[n, k] represents the k\[Null]^th zero of the Bessel function of the second kind Y_n (x).BesselYZero[n, k, x_0] represents the k\[Null]^th zero greater than x_0.
Nest
(Built-in Mathematica Symbol) Nest[f, expr, n] gives an expression with f applied n times to expr.
CompiledFunction[args...] represents compiled code for evaluating a compiled function.
CounterFunction is an option for counters that specifies the symbols used to display the value of the counter.
NearestFunction[data] represents a function whose values give the elements closest to an element that is supplied.
BesselK
(Built-in Mathematica Symbol) BesselK[n, z] gives the modified Bessel function of the second kind K_n (z).
TransformationFunction[data] represents a transformation function that applies geometric and other transformations.
MultilineFunction is an option for UnderscriptBox and related box objects that specifies what to do when the contents of a box object are too long to fit on one line.